CPR Team Performance

ABSTRACT

Systems and methods related to the field of cardiac resuscitation, and in particular to devices for assisting rescuers in performing cardio-pulmonary resuscitation (CPR) are described herein. A method for managing cardiopulmonary resuscitation (CPR) treatment to a person in need of emergency assistance includes monitoring, with an electronic medical device, a parameter that indicates a quality level of a CPR component being provided to the person by a user; determining, with the electronic medical device, that the parameter indicates that the quality level of CPR being provided is inadequate; and providing, to one or more rescuers of the person, an audible, visual, or tactile indication that a different person should perform the CPR component.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 13/474,269, filed May 17, 2012, entitled “CPR TeamPerformance”, which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

This document relates to cardiac resuscitation, and in particular tosystems and techniques for assisting rescuers in performingcardio-pulmonary resuscitation (CPR).

BACKGROUND

CPR is a process by which one or more rescuers may provide chestcompressions and ventilation to a victim who has suffered an adversecardiac event—by popular terms, a heart attack. Chest compressions areconsidered to be the most important element of CPR during the first fiveto eight minutes after CPR efforts begin, because chest compressionshelp maintain circulation through the body and in the heart itself,which is the organ that can sustain the most damage from an adversecardiac event. Generally, American Heart Association CPR Guidelinesdefine protocols by which a rescuer is to apply the chest compressionsin coordination with ventilations. For example, current 2010 AHAGuidelines specify a ratio of 30:2 for compressions toventilations—i.e., thirty compressions for every two breaths. Andcompressions are to be performed at a rate of around 100 per minute.

CPR may be performed by a team of one or more rescuers, particularlywhen the rescuers are professionals such as emergency medicaltechnicians (EMTs) on an ambulance crew. One rescuer can provide thechest compressions and another can time their ventilations of the victimto match the chest compressions according to the appropriate CPRprotocol. When professionals such as EMTs provide the care, ventilationis more likely to be provided via a ventilation bag that a rescuersqueezes, than by mouth-to-mouth. The CPR can be performed inconjunction with providing shocks to the patient from an externaldefibrillator, including from an automatic external defibrillator (AED)that is designed to be used by laypeople. Such AEDs often provideaudible information to rescuers such as “push harder” (when the rescueris not performing chest compressions forcefully enough), “stop CPR,”“stand back” (because a shock is about to be delivered), and the like.In determining how chest compressions are being performed, certaindefibrillators may obtain information from one or more accelerometers(such as in the CPR D PADZ, CPR STAT PADZ, and ONE STEP pads made byZOLL MEDICAL of Chelmsford, MA) that can be used to compute depths ofchest compression, e.g., to determine that the compressions are tooshallow to be effective and thus to cause the verbal cue “push header”to be spoken by the defibrillator.

SUMMARY

This document describes systems and techniques that may be used to helpmanage the work by teams of rescuers who are responding to a victim, orperson in need of emergency assistance. For example, typically suchteams include a pair of rescuers, where a first of the rescuers performsCPR chest compressions on the victim and the other performsventilations, either by mouth-to-mouth techniques or using a flexibleventilator bag. Frequently such teams are made up of an EMT or ambulancecrew. Also frequently, a good heartbeat cannot be established quicklyfor the victim, so that CPR must be carried out for many minutes inorder to maintain perfusion of blood in the victim. In such situations,rescuers can tire after only a minute or two of providing chestcompressions, so that certain protocols call for the rescuers to switchroles periodically. The systems and techniques discussed here areimplemented with a recognition that different people have differentlevels of skill, strength, and stamina for performing chest compressionsand other components of CPR such as ventilating a victim oradministering drugs to the victim. As a result, the techniques discussedhere monitor the quality of certain components of CPR as it is beingperformed, such as by monitoring the depth and rate of chestcompressions being performed, and they tell the rescuers to switch outwhen a component indicates that the performance of the chestcompressions or other CPR component is inadequate, and might be, orwould be, performed better by the other rescuer who is presumably more“fresh.”

In certain implementations, such systems and technique may provide oneor more advantages. For example, a patient may be provided with the bestcare that is available from the rescue team throughout a rescue episode.For example, a rescuer with greater stamina may be left performing chestcompressions longer than another rescuer with less stamina, whereas theymight have been allowed to perform for equal time periods, withsubstandard performance, using techniques other than those describedhere. Also, the terms of each cycle may change as the rescuecontinues—e.g., by shortening the cycles as each of the rescuers getsmore tired. Such adjustments may be dynamic and need not rely on astatic timed schedule. Also, the system may identify erosion inperformance even when the rescuers themselves do not recognize thattheir performance has eroded. Such identification may occur by measuresexternal to the rescuer, such as their rate and depth of providing chestcompressions, or measures internal to the rescuer, such as by measuringtheir blood oxygen level and pulse rate. The instructions to switch mayalso be provided in a clear and simple manner (and in a variety ofmanners, such as audibly or on a visual display next to the hands of therescuer performing chest compressions), so that even rescuers in ahigh-stress environment can get the message (and the instructions can beprovided at an increasing severity level if the system determines thatthe rescuers are not responding to the original instructions). Moreover,in certain implementations, such techniques can be used on teams of two,three, or more rescuers. In addition, in certain implementations, thetechniques described here can be implemented as part of an automaticexternal defibrillator (AED) or a professional defibrillator, or in adual-mode defibrillator. As a result, the clinical performance of arescuing team can be increased, and patient outcomes improved.

In one implementation, a method for managing cardiopulmonaryresuscitation (CPR) treatment to a person in need of emergencyassistance is disclosed. The method includes monitoring, with anelectronic medical device, a parameter that indicates a quality level ofa CPR component being provided to the person by a user; determining,with the electronic medical device, that the parameter indicates thatthe quality level of CPR being provided is inadequate; and providing, toone or more rescuers of the person, an audible, visual, or tactileindication that a different person should perform the CPR component. Themethod may also comprise repeating cyclically the actions of monitoring,determining, and providing, while multiple different people areinstructed to perform the CPR component. The CPR component can comprisechest compressions, and the parameter comprises depth of compression,rate of compression, or both. In some aspects, the method also comprisesgenerating a chest compression quality score from a combination of chestcompression rate and chest compression depth, and providing theindication in response to the quality score falling outside a determinedacceptable range.

In certain particular aspects, the method further comprises providinginformation about a target chest compression depth with the electronicmedical device, or providing periodic feedback to the user by displayingon a graphical display screen of the electronic medical device, anindication of values for depths of one or more of a plurality of chestcompressions and an indication of a target compression depth. Providingthe periodic feedback can also comprise displaying on a graphicaldisplay screen of a defibrillator, a graphical representation of thedepths of one or more of the plurality of the chest compressions and anindication of the target compression depth. Separately, providing theperiodic feedback can further comprise displaying on a graphical displayscreen of a defibrillator, a graph having a visual indicia representingthe target compression depth and visual indicia representing the valuesfor the depths of one or more of the plurality of the chest compressiondisplayed above or below the visual indicia representing the targetcompression depth.

In yet Other aspects, the method can also comprise displaying, on afirst electronic display located on a thorax of the person in need ofemergency assistance, information that provides instructions forperforming CPR to one of the rescuers. And display may be made, on asecond electronic display and to another of the rescuers, of informationthat provides instructions for performing CPR to one of the rescuers,the information provided on the first electronic display differing fromthe information provided on the second electronic display. Theelectronic device can also be connected to a defibrillation electrode onthe person in need of emergency assistance. Moreover, the method caninclude providing, to a first of the one or more rescuers, an indicationabout the quality of chest compressions given to the patient, theindication about the quality chest compressions differing from theindication that a different person should perform the CPR component. Yetin other implementations, the method comprises identifying a protocolfor CPR being performed by the rescuers, and coordinating the providingof the indication that a different person should perform the CPRcomponent with stored parameters that define the protocol, wherein theidentified protocol is select from among multiple protocols stored onthe electronic medical device.

In another implementation, a system is disclosed for managingcardiopulmonary resuscitation (CPR) treatment to a person in need ofemergency assistance. The system comprises an electronic patientmonitor; a sensor interface on the monitor arranged to receive inputfrom one or more sensors that sense one or more that indicate a qualitylevel of one or more CPR components being provided to the person in needof emergency assistance; a CPR monitor in the electronic patient monitorprogrammed to use the input from the sensors to identify a qualityparameter and to generate a signal to switch rescuers performing CPRwhen the quality parameter meets a determined criterion; and an outputinterface in communication with the CPR monitor and arranged to providerescuers using the electronic patient monitor with an indication toswitch rescuers, in response to receiving the generated signal from theCPR monitor. The electronic patient monitor can be part of an externalpatient defibrillator, and the output interface can comprise anelectronic display attached to a connector that also is attached todefibrillator electrodes for connection to the external patientdefibrillator. Moreover the electronic display can be attached to one ofthe defibrillator electrodes and arranged so as to rest adjacent arescuer's hands when the electrode is properly placed on the person inneed of emergency assistance, and the rescuer's hands are placed forperforming CPR chest compressions. In some aspects, the CPR monitorcomprises a microprocessor connected to electronic memory that storesinstructions that when executed perform a process of identifying aquality parameter and generating a signal to switch rescuers performingCPR when the quality parameter meets a determined criterion.

In some other aspects, the system also comprises a sensor arranged tosense a quality level of chest compressions performed on the person isneed of emergency assistance. The CPR monitor can also be furtherprogrammed to repeat cyclically actions of identifying the qualityparameter, determining whether the quality parameter indicates a need toswitch rescuers, and generating a signal to switch rescuers when thequality parameter indicates a need. And the quality parameter canreflect a depth of chest compressions, rate of compression, or both, ofchest compressions performed on the person in need of emergencyassistance. The system can also comprise a display arranged to providefeedback to a rescuer indicating a way to improve the one or more CPRcomponents. Moreover, the output interface can comprise a wirelesstransmitter arranged to communicate data regarding the one or more CPRcomponents to a rescuer of the person in need of emergency assistance.In addition, the first interface can be arranged to communicate with afirst display device for use by a first rescuer, and further comprisinga second interface arranged to communicate with a second display devicefor use by a second rescuer, the second display device to communicateinformation about a CPR component that is different than informationabout a CPR component that is displayed on the first display device.Finally, the system can further comprise identifying a protocol for CPRbeing performed by the rescuers, and coordinating the providing of theindication that a different person should perform the CPR component withstored parameters that define the protocol, wherein the identifiedprotocol is select from among multiple protocols stored on theelectronic medical device.

Other features and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is an overhead view of rescuers performing CPR on a victim usingan electronic system that instructs them in performance of the CPR.

FIGS. 2A and 2B show a portable defibrillator and ancillary componentsarranged to provide feedback and instruction to rescuers.

FIGS. 2C-2E show chest compression pucks that can capture informationfrom a rescuer.

FIG. 3 shows example chest compression inputs and mechanisms foranalyzing the inputs to determine whether a different person shouldprovide chest compressions.

FIG. 4 is a flowchart of a process for monitoring CPR performance andproviding feedback for improvement of the performance.

FIGS. 5A and 5B illustrate a defibrillator showing certain types ofinformation that can be displayed to a rescuer.

FIGS. 6A-6C show screenshots of a defibrillator display that providesfeedback concerning chest compressions performed on a victim.

FIGS. 7A and 7B show screenshots providing feedback regarding aperfusion zo index created form chest compressions.

FIGS. 8A and 8B show screenshots with gradiated scales indicating targetchest compression depths.

FIG. 9 shows a general computer system that can provide interactivitywith a user of a medical device, such as feedback to a user in theperformance of CPR.

DETAILED DESCRIPTION

This description discusses systems and techniques for guiding theprovision of care to a patient, such as the provision of CPR to a victimof cardiac arrest. For example, a portable electronic defibrillator maybe provided to rescuers and may include common features for deliveringdefibrillating energy (a shock) to a victim of cardiac arrest throughelectrodes that may be placed on the torso of the victim. Thedefibrillator may also be provided with a mechanism for sensing themanner in which CPR chest compressions are performed on the victim, suchas a puck or similar item that includes an accelerometer and may beplaced under the hands of the person performing chest compressions andon top of the sternum of the victim. The defibrillator may useinformation from such an item to identify the depth and rate of chestcompressions that are being performed by a rescuer, and may identifywhen such information indicates that the rescuer is tiring, such as whenthe depth of compressions is inadequate for a time period, and the rateof compressions begins to slow. Also, the system may look to internalfactors of the rescuer such as pulse and blood oxygen level, in makingthe determination. When the defibrillator makes a determination that thechest compressions are inadequate due to fatigue on the part of therescuer, the defibrillator may provide an indication to that rescuerthat he or she should step away and allow another rescuer to performchest compressions for a time. For example, where there are tworescuers, the other rescuer may have been providing ventilation to thevictim using a ventilation bag, and may be simultaneously prompted toturn and provide chest compressions, while the first rescuer takes overoperation of the bag.

FIG. 1 is an overhead view of rescuers 104, 106 performing CPR on avictim 102 using an electronic system that instructs them in performanceof the CPR. In this example, rescuers 104, 106 are already in positionand providing care to the victim 102, with rescuer 104 in position andproviding chest compressions to the torso of the victim 102, and rescuer106 providing ventilation using ventilation bag 112. The rescuers 104,106 may be lay rescuers who were in the vicinity of the victim 102 whenthe victim 102 required care, or may be trained medical personnel, suchas emergency medical technicians (EMTs). Although two rescuers are shownhere for purposes of explanation, additional rescuers may also care forthe victim 102, and may be included in a rotation of rescuers providingparticular components of care to the victim 102, where the componentsmay include chest compressions, ventilation, administration of drugs,and other provision of care.

In some examples, one or more therapeutic delivery devices (not shown)can automatically deliver the appropriate therapy to the patient. Thetherapeutic delivery devices can be, for example, a portable automaticchest compression device (e.g., with a belt that wraps around thevictim's chest), a drug infusion device, an automatic ventilator and/ora device that includes multiple therapies such as defibrillation, chestcompression, ventilation, and drug infusion. The^(:)therapeutic deliverydevices are physically separate from the defibrillator 108, and controlof the therapeutic delivery devices may be accomplished by acommunications link from the defibrillator 108 that may be wired,wireless, or both.

In other examples, control and coordination for the overallresuscitation event and the delivery of the various therapies may beaccomplished by a device or processing element that is external to thedefibrillator 108, such as by use of a tablet-based computer that iscontrolled by one of the rescuers. For instance, the device may downloadand process ECG data from the defibrillator 108; analyze the ECGsignals, perform relevant determinations like those discussed above andbelow based on the analysis, and control the other therapeutic devices.In other examples, the defibrillator 108 may perform all the processingof the ECG, including analyzing the ECG signals, and may transmit to aseparate device only the final determination of the appropriate therapy,whereupon the separate device can perform the control actions on theother linked devices.

An electrode assembly 110 is shown in position on the victim 102 in anormal position. The electrode assembly 110, in this example, is anassembly that combines an electrode positioned high on the right side ofthe victim's torso and an electrode positioned low on the left side ofthe victim's torso, along with a sensor package located over thevictim's sternum. The sensor package, which is obscured in the figure bythe hands of rescuer 104 in this example, may include an accelerometeror similar sensor package that may be used in cooperation with acomputer in the defibrillator 108 to generate an overall quality scorefor the chest compression, and the quality score may indicateinstantaneous quality or average quality across a time.

The score may indicate when and how the rescuer 104 is performing chestcompressions on the victim 102, based on signals from the sensorpackage. For example, as a simplified description, signals from anaccelerometer may be double integrated to identify a verticaldisplacement of the sensor package, and in turn of the sternum of thevictim 102, to identify how deep each chest compression is. The timebetween receiving such input from the sensor package may be used toidentify the pace at which chest compressions are being applied to thevictim 102.

The defibrillator 108 in this example is connected to the electrodepackage 110 and may operate in a familiar manner, e.g., to providedefibrillating shocks to the electrode package 110. As such, thedefibrillator may take a generally common form, and may be aprofessional style defibrillator, such as the R-SERIES, M-SERIES, orE-SERIES from ZOLL Medical Corporation of Chelmsford, Mass., or anautomated external defibrillator (AED), including the AED PLUS, or AEDPRO from ZOLL Medical Corporation. The defibrillator is shown in oneposition relative to the rescuers 104, 106 here, but may be placed inother locations to bette present information to them, such as in theform of lights, displays, vibrators, or audible sound generators on achest-mounted component such as an electrode or via an addressableearpiece for each of the rescuers. Such feedback, as discussed morefully below, may be on units that are separate from the main housing ofthe defibrillator, and that may communication information about thevictim 102 and performance of CPR to the defibrillator 108 or mayreceive feedback information from the defibrillator 108, through eitherwired or wireless connects that are made directly with the defibrillator108 or indirectly through another device or devices.

For illustrative purposes, two particular examples of feedback are shownhere on a display of the defibrillator 108. First, a power arrow 114provides feedback to the rescuer 104 regarding the depth of compressionthat the rescuer 104 is applying in each compression cycle to the victim102. In this example, power arrow 114 is pointing upward, and thusindicating to rescuer 104, that rescuer 104 needs to apply more vigorousinput to create deeper chest compressions. Such feedback may be onlyprovided visually for performing chest compressions, in order tominimize the amount of information that the rescuer 104 must deal within a stressful situation. For example, an arrow indicating to apply lesscompression may not be shown under an assumption that very few rescuerswill apply too much compression, and thus the user need only respond toindications to apply more pressure. The particular type of feedback tobe provided can be determined by a designer of the defibrillator 108 andmay vary to match particular situations.

Separately, the rescuer 104 may be provided with additional limitedfeedback, such as feedback for performing chest compressions at anappropriate rate. As one example, the defibrillator 108 may emit a soundthrough speaker 118 in the form of a metronome to guide the rescuer 104in the proper rate of applying CPR. A visual representation may alsoindicate rates for performing compressions, such as a blinking of thedisplay on defibrillator 108. In addition, or as an alternative outputmechanism that is designed to avoid distracting rescuer 106, hapticfeedback may be provided to rescuer 104 through electrode assembly 110.For example, a puck or other item on which the rescuer 104 places herhands may be provided with mechanisms for vibrating the puck similar tomechanisms provided for vibrating portable communication devices (e.g.,when an incoming telephone call is received on a smartphone). Suchvibrating may be provided so as to minimize the amount of informationthat can distract other rescuers in the area, and may also more directlybe used by the rescuer 104 to synchronize her chest compressionactivities with the output. For example, the vibrations may be periodic(approximate 100 times per minute) at the rate of performing chestcompressions when the rescuer 104 should be performing compressions andmay stop or be vibrated constantly when the rescuer 104 is to stop andswitch positions with another rescuer, such as rescuer 106. Withfeedback provided at the rescuer's hands, and because the rescuer 104 isproviding the chest compressions with her hands directly, input by thesystem into her hands may be more directly applied with respect to therescuer 104 keeping an appropriate pace. Such haptic feedback may alsorelieve the rescuer 104 of having to turn her head to view the displayon defibrillator 108. Thus, a first type of feedback, such as pulsedvisual, audible, or tactile feedback may be provided to guide a user inperforming CPR, and that type of feedback may be interrupted andreplaced with a different type of feedback such as constant sound orvibration to indicate that a rescuer is to stop performing theparticular component of CPR and let someone else take over.

Cycling arrows 116 are shown separately on the display of thedefibrillator 108. Such arrows may indicate to the rescuer 104 and tothe rescuer 106 that it is time for them to switch tasks, such thatrescuer 104 begins operating the ventilation bag 112 (as shown by thearrow superimposed over the legs of rescuer 104 to indicate that shewould slide upward toward the victim's head, rotate the bag 180 degreesand begin operating it), and rescuer 106 begins providing chestcompressions on electrode assembly 110. Where there are three or morerescuers, the third rescuer may have been resting, and may take overchest compressions for rescuer 104 when a rescuer change is directed bythe system, and the rescuer 104 may then the rest or may take the bagwhile rescuer 106 rests or does something else. For example, therescuers may readily determine that rescuer 106 does not have thestrength to provide consistent chest compressions on the victim 102, andmay determine that rescuer 106 should constantly provide ventilationusing ventilation bag 112, while other rescuers switch out in providingchest compressions. Thus, when the arrows 116 are displayed, rescuer 106may stay in place while two other rescuers switch places with respect todelivering chest compressions. In the examples, discussed here, thesystem may be programmed to be indifferent to the manner in whichrescuers decide to rotate, and the rotation may change during a rescue(e.g., rescuer 106 may initially provide chest compressions as part of a3-person rotation and may then bow out and just provide ventilationwhile the other 2 rescuers rotate on chest compressions).

The defibrillator 108 may cause the cycling arrows 116 to be displayedbased on the occurrence of various events. In one example, the cyclingarrows 116 may be displayed after a set time period has elapsed sincerescuer 104 began applying chest compressions. For example, a particularCPR protocol may require switching of rescuers at certain predefinedperiodic intervals (e.g., every 2 minutes). As described below in moredetail, the cycling arrows 116 or a similar cycling signal, mayalternatively be generated according to determinations made by thedefibrillator 108 regarding the quality of chest compressions beingprovided to the victim 102 by rescuer 104, including by monitoring pastcompression parameters (e.g., rate over several compressions and depth)and monitoring the rescuer directly (e.g., by determining a pulse andblood oxygen level of a rescuer). Such an analysis may recognize thatrescuers tire progressively over time as they are providing chestcompressions, so that the depth of chest compressions is likely to fallover time, and the rate of chest compressions may also fall or becomemore erratic over time.

The defibrillator 108 may thus be programmed to identify when suchfactors indicate that the chest compression ability of the rescuer 104has fallen, or is about to fall, below a level that is of adequateeffectiveness. As discussed below, for example, a score may be generatedfor the depth of compression based on how far from optimal compressioneach of the rescuer's 104 compressions are. Another score may begenerated based on how far from optimal the rate of compressions are,and the two scores (depth and rate) may be combined to generate anoverall quality score for each compression. A third score may indicatethe rescuer's 104 physical state (e.g., via pulse measurement) and thatscore may also be combined. A running quality score may then be computedto indicate the quality of compressions over a period of time, such asover the last several compressions made by the user, so as to betterindicate a trend in the quality of chest compressions being provided (inthe past, the near future, or both). When the quality score falls belowa threshold, the defibrillator 108 may then generate an indication thatthe current rescuer 104 should stop performing chest compressions andallow someone else to take over, such as by displaying cycling arrows116.

Similarly, the quality of ventilation may be monitored. For example,providers of ventilation may tire and forget that they are squeezing aventilation bag too frequently—at too high a rate. They may be remindedinitially, such as by a beeping metronome tied to the proper rate, or anLED on the bag that blinks at the proper rate. As with reminders forchest compression, such a reminder may be provided constantly, whetherthe user is performing properly or not, or can be triggered to startwhen the user is initially identified as performing in a substandardfashion. Subsequently, if the substandard performance continues for apredetermined time period or deteriorates to a second threshold level;the performance trends in a manner that indicates the user is not likelyto improve the performance; or the performance otherwise indicates thatthe provider of ventilation should be switched out, a switchingindication may be generated. Also, whether for compression orventilation, different colors of lights may be used to indicatedifferent types of feedback, such as a green light for good work, ayellow light to indicate a temporary deviation from good work, and a redlight or even a blinking red light to indicate that the rescuer shouldswitch out with someone else.

Where the providers of chest compressions and of ventilation are bothbeing monitored in such a manner, a signal to switch may be generatedwhen the first provider hits a substandard level. Alternatively, ifchest compressions are considered more important than is ventilation,the level at which ventilation will trigger a switch can be set muchmore below a level considered to be satisfactory as compared to a levelfor chest compressions. In other words, a system may be biased to letthe “weak” rescuer continue performing ventilation, rather thanswitching to a situation in which a somewhat fresh, but nonethelesstired with respect to squeezing a bag, and weak rescuer is placed in themost important position over another rescuer who may be more tired butis overall stronger at performing chest compressions. Various mechanismsmay be used to balance the multiple factors, which include the relativeimportant of each component to patient outcomes, the relative strengthof each rescuer, the current performance and trending of performance foreach rescuer, and knowledge or performance and trending for each rescuerfrom prior rescues (e.g., if the rescuers 104, 106 are part of an EMTteam that uses the same defibrillator multiple times, or who have theirdata from multiple rescues uploaded to a central system for analysis) orprior cycles in the same rescue.

The process of observing the quality of a component of the CPR, such asthe quality of chest compressions, may then continue recursively as longas care is being provided to the victim 102. For example, after thedefibrillator 108 generates an indication to switch providers of chestcompression, the defibrillator 108 may sense through the electrodepackage 110 that chest compressions stopped for a period, thusindicating that users have switched as suggested by the defibrillator108. Once chest compressions then start again, the defibrillator 108 mayagain begin determining a quality score for chest compressions providedby the new rescuer, and may indicate that rescuers should switch againwhen the quality falls. In certain instances, an indication to switchmay be blocked from being generated for a certain period after a newuser begins performing compressions, under the assumption that the usermight not be tired, but is merely trying to establish a rhythm inperforming the chest compressions. Also, trends in the quality of theparticular CPR component may be tracked rather than absolute values ofthe performance, so that the defibrillator 108 can distinguishsituations in which a rescuer is giving a poor chest compressionsbecause he or she was trying to find the appropriate rhythm or wasdistracted by a temporary problem, from situations in which the usertruly is tiring and should be replaced.

In certain instances, the defibrillator 108 may be adaptable todifferent CPR protocols. For example, the defibrillator 108 may beprogrammed according to a protocol that, among other parameters, callsfor each rescuer to provide chest compressions for a preset period oftime. In such a situation, the defibrillator 108 may use pauses in theprovision of chest compressions to determine when users have switchedproviding chest compressions, and may start a timer based on suchobservation. When the timer hits the preset period, the defibrillator108 may then provide an indication that the rescuer giving chestcompressions is to change. The timer may then be reset once a nextrescuer is identified as having started giving chest compressions, suchas by recognizing a pause in the provision of chest compressions.

Other protocols may be more flexible and may allow switches in rescuersto be dependent on the performance of the rescuers in addition to apredefined time interval. For example, the defibrillator 108 may beprogrammed to indicate that rescuers should change when it senses thatperformance has fallen below an acceptable level, and may also indicatethe need for change when a maximum preset time has occurred even if thecurrent rescuer appears to be performed well. In such a protocol, thetime interval may be substantially longer than an interval for aprotocol that requires changing based only upon elapsed time, and notupon degraded performance by the rescuer. Various different protocolsmay call for changing of rescuers based on different levels inperformance, or upon different elapsed time periods, or a combination ofthe two. In particular, AHA protocols are generally just guidelines, anda particular medical director may alter such guidelines to fit theirparticular needs or professional judgment. (Indeed, revisions to AHAguidelines typically come from forward-thinking people who makemodifications to prior guidelines and find the modifications to beeffective.)

In such a situation, the defibrillator 108 may be programmed with theparameters for each of the protocols, and an operator of thedefibrillator 108 may select a protocol to be executed by thedefibrillator 108 (or the protocol may have been selected by a medicaldirector). Such a selection may occur at the time of a rescue, or at aprior time. For example, the ability to select of a protocol may belimited to someone who logs onto the defibrillator 108 or configurationsoftware separate from defibrillator 108 using administrator privileges,such as a person who runs an EMT service (e.g., a medical director ofappropriate training and certification to make such a determination).That person may select the protocol to be followed on each of themachines operated by the service, and other users may be prevented frommaking such changes. In this manner, the defibrillator 108 may be causedto match its performance to whatever protocol its users have beentrained to.

Thus, using the techniques described here, the defibrillator 108 may, inaddition to providing defibrillation shocks, ECG analysis, and otherfeatures traditionally provided by a defibrillator, also provideindications to switch rescuers between various components of providingCPR and other care to a patient. The defibrillator may be deployed inthe same manner as are existing defibrillators, but may provideadditional functionality in a manner that can be easily understood bytrained and untrained rescuers.

FIGS. 2A and 2B show a portable defibrillator and ancillary componentsarranged to provide feedback and instruction to rescuers. Each of thefigures shows an example in which visual feedback can be provided to arescuer from a location that is away from the defibrillator unit, andmore immediately in the line of sight and focus of attention of arescuer, such as a rescuer who is providing CPR chest compressions.

Referring to FIG. 2A, a system 200 is shown in which a defibrillator202, which takes a standard form, but is provided with additional userfeedback functionality, is connected to an electrode assembly by way ofa wiring harness 204. The wiring harness 204 may include a number ofwire leads that are connected together by a common plastic shroud thatmay surround the wires or may have been integrally formed around thewires such as through an extrusion process, and may be connected to thedefibrillator 202 by way of a single plug. For example, thedefibrillator 202 may be provided with a female or male connection, andthe plug may be provided with a corresponding connection in a mannerthat is well known in the art. The wires may carry power from thedefibrillator 202, such as current to provide a shock to a victim who isbeing provided with emergency care, or to the defibrillator 202, such asin the form of signals for generating ECG information, accelerometerinformation, and measurements of trans-thoracic impedance of a victim.

The electrode assembly in this example includes a first electrode 206, asecond electrode 208, and a chest compression assembly 210. The firstelectrode 206 may be configured to be placed above the victim's rightbreast, while the second electrode 208 may be configured to be placedbelow the victim's left breast. During a rescue operation, printedinsignia on one or both of the electrodes 206, 208 may indicate to arescuer how to deploy the electrodes 206, 208, and where each of themshould be placed. In addition, the defibrillator 202 may display suchinstructions on a graphical display and may also provide verbalinstructions to supplement was is shown in the visual instructions, suchas instructions for the sequential operation of the defibrillator.

The chest compression assembly 210, in this example, includes a detector212 and a display 214. The detector 212 may include a plastic housingwithin which is mounted an accelerator assembly. The acceleratorassembly may move with the housing as chest compressions are performedon a victim so that motion of the accelerometer matches motion of thevictim's sternum. The detector 212 is shown in the figure as having an“X” printed on its top surface to indicate to the rescuer where to placehis or her hands when delivering chest compressions to a victim. Theaccelerator in the housing may be connected to pass signals throughharness 204 to defibrillator 202 (or may include a wireless transceiverfor passing the information wirelessly), which may be provided withcircuitry and or software for converting such signals into theindications about the rate and depth of compressions being performed onthe victim, in manners such as those described below.

The display 214 may provide feedback that is directed to the rescuer whois performing chest compressions. In this example, the feedbackcomprises symbols similar to those shown on the display of defibrillator108 in FIG. 1, in particular, an arrow indicating when the user is toperform chest compressions more vigorously, and circular cycling arrowsindicating when rescuers are to switch in performing chest compressions.The particular symbols used may be selected also to be independent ofthe orientation from which they are viewed (as the cycling arrows arehere), so that the symbols may have the same meaning to a rescuer who ison the right side of the victim as to a rescuer who is on the left sideof the victim. In that manner, the system 200 does not need to determinewhere the rescuer is positioned. Also, a haptic vibrating mechanism maybe provided at the assembly 210, so as to provide tactile beats ormetronomes for a user to follow in providing chest compressions. Incertain instances, when the unit indicates that rescuers are to switch,such haptic or tactile feedback may be turned off or provided as aconstant vibration so as to provide an additional indication to therescuer that they should no longer be performing chest compressions.

FIG. 2B shows a slightly different arrangement in a system 216 thatincludes a defibrillator 218 that is the same as defibrillator 202. Inactual implementation also, the same defibrillator could be used withtwo different types of electrode assemblies like those shown here inFIGS. 2A and 2B. With specific reference to FIG. 2B, a wiring harness220 in this example may be the same as wiring harness 204 in FIG. 2A,though here it connects defibrillator 218 to an electrode 224, and anassembly 226. The electrode 224 may simply be a single electrode that isconnected to receive energy from the defibrillator 218, and is arrangedto be placed in a conventional manner above a victim's right breast. Theelectrode 224 may also include mechanisms for sensing an ECG readingfrom a victim, and for communicating sensed parameters back to thedefibrillator 218.

The assembly 226 may take a slightly L-shaped form, with one legcomprising an electrode designed to be placed below a victim's leftbreast, and another leg arranged to lie in a line with the victim'ssternum. The assembly may be mounted on a flexible foam later thatincludes a gel layer on the bottom of the electrode for conducting ashocking pulse to a victim, but no gel under the sensor portion.However, the sensor portion may have a form of adhesive on its bottomside so that the accelerometer does not bounced and separate from thevictim during chest compressions, and thus give an inaccurate reading tothe defibrillator 218.

In this example, the hypothetical victim is shown in dotted lines toindicate how the electrode 224 and the assembly 226 may be positioned inactual use. Before they are deployed, however, the various electrodesand assemblies may be stored in a sealed packet, and the wires may becoiled to reduce needed space, in conventional manners. At the time ofan emergency, the wires may have already been plugged into thedefibrillator (e.g., via the wires extending through a sealed hole outof a packet in which the electrodes are stored to keep their gelsmoist). A rescuer can then open the package, plug the wires in if theyare not already plugged in, and if necessary, read instructions on theback sides of the electrodes regarding the proper manner to apply theelectrodes—e.g., with graphics that show the peeling off of covers overthe electrode gels and also show images of the proper placement of theelectrodes on a line-drawn victim.

In additional to electrodes, the assembly 226 may include a sensorassembly 228 and a display 230, similar to the sensor assembly 212 anddisplay 214 in FIG. 2A. In addition, the components that providefunctionality of the assembly 228 and display 230 may be the same asthose described above for assembly 212 and display 214 in FIG. 2A. Inthis example, though, the assembly 228 and display 230 are connecteddirectly to the electrode 226 by flexible structures that are arrangedand sized so as to place the electrode and sensors in appropriatelocations for a victim (under a left breast and aligned over the top ofthe sternum). Such an arrangement allows the system 216 to have fewercomponents that need to be applied to a victim then the system 200,while still having the flexibility to space the two electrodes relativeto each other depending on the size of the victim—i.e., because theelectrodes are separate from each other, it may be easier to positionthem both on small victims and very tall/long victims.

In both of the systems 200, 216, the placement of a display near thehands of a rescuer may provide one of more benefits in certainimplementations. For example, a rescuer is typically looking at his orher hands when applying chest compressions, both because it is mostnatural to look forward, and as a mechanism to obtain feedback on howdeep the chest compressions are and how the victim is doing. Thus, therescuer can see the feedback without having to look around, and canconstantly receive the feedback even while performing chestcompressions. Also, the components can be provided in such locationsconveniently and with relatively low cost, since the electrodes andaccelerometers will already be provided, and a display need simply beadded to one of these existing components (though in otherimplementations, the display may be located elsewhere). The feedbackdevice also is naturally positioned to provide haptic feedback, whichmight be more directly processed by a rescuer. And by using visualfeedback that is in the field of view of a particular rescuer and usinghaptic feedback, the system can reduce “attention pollution” at a scene,in that is lessens the level of noise and other distractions that otherrescuers have to deal with in a very stressful environment.

Feedback devices away from the main medical device may also take otherforms. For example, an LED may simply be provide in the top surface ofone of the electrodes or near a puck, and the LED may blink to indicatea rate of chest compressions to be performed, and stay solid on toindicate that rescuers should switch positions. Also, an LED orgraphical display may be provided on the ventilation bag 212, such as toblink to indicate a rate at which the bag is to be squeezed, and may bemade solid in coordination with a display for the person performingchest compressions being made solid. In other words, the same signal canbe provided to each of the rescuers to switch places, though on therespective sub-system that they are currently operating. As a result,the rescuers will only need to know a single “change” signal and will beable to react more intuitively and more quickly.

FIGS. 2C-2E show chest compression pucks that can capture informationfrom a rescuer. In general, typical pulse oximetry sensor components maybe integrated into a device on or in which a rescuer places his or herfingers, and can be used to provide a connected (wired or wirelessly)medical device such as a defibrillator, with indications of the bloodoxygen level and pulse rate of a rescuer holding the device, which inthese examples can be referred to as a CPR puck. The pucks shown heremay be provided as part of the systems also shown in FIGS. 2A and 2B,such as by integrating the components for sensing rescuer condition intothe components in those other figures.

Referring now specifically to FIG. 2C, there is shown an assembly 232made up of a puck housing 336 and substrate 234. The substrate 234 mayhave on its lower side an gel-based adhesive so that the assembly 232adheres to the chest of a victim on which it is placed. The housing 336may in turn be solidly adhere to the top of the substrate 234 do thatthe housing 336 moves with a victim's sternum when a rescuer places hisor her hands on top of the “X” shown on the top surface of the housing236 and performs chest compressions. Connected to the substrate 234and/or housing 336 by wire is a pulse oximeter 238. The pulse oximetermay report a blood oxygen level and pulse rate through the wire fromwhich hit is attached into the remainder of the assembly 232, from whichit may be reported to a defibrillator or other medical device, eitherwirelessly or by wired connection.

In operation, when a rescuer begins performing chest compressions, he orshe may be instructed to slip a fingertip into the pulse oximeter 238before placing his or her palms on top of the housing 336. The wire maypermit movement of the rescuer's fingertip as they perform chestcompressions, while measuring the relevant values. Such values may thenbe used, as discussed above, along with other factors such as rate anddepth of compressions, to determine when the rescuer should beinstructed to stop performing chest compressions and yield to anotherrescuer. Also, the assembly 232 may be provided as a stand-alone unitseparate from a defibrillator or other medical, so as to provide moregeneral feedback to a rescuer, where the feedback integratesconsideration of rescuer blood oxygen level, pulse, or both.

Referring to FIGS. 2D and 2E, there is shown a top and side section viewof an assembly 240 that is similar to assembly 232 in FIG. 2C, butintegrates sensing functionality for the rescuer into the puck housing.

Again, the housing is shown on top of an adhesive substrate 242, but inthis example, the housing is provided with depressions 244 a, 244 b intowhich a rescuer can slide his or her fingertips while performing chestcompressions, as shown by the hand in FIG. 2E. The housing is providedhere with depressions 244 a, 244 b on opposed sides, so that rescuers onboth sides of a victim may use the assembly 240 and take advantage ofits rescuer monitoring functionality. Also, as shown, sensors 250 can beprovided at multiple locations, including four different locations toreflect rescuers who may be on either side of the victim and may placesfingers from their right or left hands into the depressions 244 a, 244b.

The assembly may simply send signals back to a medical device such as adefibrillator. Separately, the assembly 240 may modify or analyze thesignals right on the assembly 240 in the housing. Thus, for example, aoximeter processor 248 is shown inside the housing and may receivesignals from the sensors 250 and convert them partially or fully intoblood oxygen and pulse rate values that can then be displayed or furtherprocessed on the assembly 240 (e.g., to identify that the rescuer isbecoming fatigued). Similarly, an accelerometer pack 246 may be providedinside the housing in a position so as to sense proper motion of thevictim's sternum. The pack 246 may, for example, compute depths ofcompressions and rates of compressions, and may also be connected to anoutput mechanism on the assembly 240 or connected to a medical devicethat is separate from the assembly 240 so as to provide chestcompression feedback in manners like those discussed above and below.

FIG. 3 shows example chest compression inputs and mechanisms foranalyzing the inputs to determine whether a different rescuer shouldprovide chest compressions. In general, the example here shows a seriesof eighteen chest compressions 300 that have been graphed along ahorizontal time axis, along with a variety of numbers that representparameters of how the chest compressions were performed. Such sensedcompression data and derived numbers may then be used to determine whenthe quality of the chest compressions indicates tha the rescuer isgetting fatigued, and the system should indicate to the rescuer thatthey should switch with another, fresher rescuer.

Referring more specifically to the graphed compressions, a dashed line302 represents a target chest compression depth and each of the spikes304 here indicate a distance level of downward compression (y axis),graphed according to time (x axis). In particular, the compressions aresharp motions followed by pauses, with the overall pattern repeatedeighteen times during the time (which may be a fraction of a minute whenthe rescuer is performing about 100 compressions per minute). Suchcompressions may be sensed by an accelerometer assembly that is betweenthe hands of the rescuer performing chest compressions and the sternumof the victim. Sensed signals may then be passed through a wiringharness to circuitry and software in a defibrillator or other medicaldevice that can analyze the signals to identified compression depths andtiming of the chest compressions.

As can be seen, the initial chest compressions are at an appropriatelevel and an appropriate rate, but began to dip at the fourth and fifthcompressions. The compressions then pick up and hit the dashed line 302,perhaps because the fall in compressions caused a defibrillator toindicate to a rescuer that they should compress harder, and the userfollowed such direction. The depth of compressions over time then fallsagain at compressions 11, 12 and 13, but then picks up at 14 and fallsyet again near the end, indicating that the user has become fatigued.

Below the graph are shown numbers that, for this example, indicatevalues that may be computed by a defibrillator that is connected to asystem for determining when to signal that a provider of chestcompressions to a victim should be changed by the system. The top rowshows a score that may be given to a user to rate the quality of thedepth of the chest compressions. Such a score may be given a baseline of100 around a depth that approximates the desired line of 302. The scoremay fall the further one gets from line 302, though the score may fallmore quickly for deviations on the under-compression side than theover-compression side, e.g., if a determination is made thatunder-compression is a more serious error than over-compression. Thus,for example, the fifth compression falls below line 302 by an amountless than the sixth compression falls above the line, but the fifthcompression receives a lower score than does the sixth compression.

In this example, the depth of compression factor is provided 70% of aweighting in determining an overall score for the quality of the chestcompression. The other 30% of the score is driven by the rate at whichthe user provides the compressions. Thus, for example, one can seefairly even spacing for compressions two through eight, but a slightdelay for compression nine, so that the ninth compression receives ascore of 90 instead of a score of 100. In addition, one can seelengthening delays between compressions at the end of the period. Therate scores reflect, in each instance, how far a compression wasperformed from the time at which it was supposed to be performedaccording to protocol. Again, the scores are scaled to a maximum of 100for ease of explanation, but could take other forms also.

The third line in the numbers indicates an overall score for each of thecompressions, where the overall score is simply the combined weightedvalue of the two component scores for depth and rate, respectively.Finally, the fourth line shows a running score that is a running averageof the current score and the two previous scores. By using a runningaverage, singular deviations from a perfect compression may be ignored,while lingering deviations can be captured so that continual failure bya user, which indicates fatigue of the user, can result in thegeneration of a signal to switch users in performing chest compressions.Thus, for example, compression number five is a bad compression, but therunning score is relatively high because the previous two compressionswere better.

In this example, the trigger for generating an indication that usersshould change position is a running score at or below 85. Thus, althoughthe running score in the example rises and falls as a user has periodicproblems with performing compressions, it does not fall to thetriggering level until compression eighteen, after there had been threeweak compressions in a row that were also spaced too far apart—so thatthe running average score really fell. In actual implementation,software may monitor the value as a user provides compressions, mayperiodically update the value (e.g., once for each compression or onanother basis), and may cause a defibrillator, such as defibrillator108, to emit output to one or more rescuers to indicate the need for achange, such as the indication shown in the prior figures above.

While the particular running average scoring technique described here isprovided for its simplicity and ease of understanding, differentapproaches may be used to identify when a user is likely becoming toofatigued to maintain quality chest compressions or other components ofCPR. For example, various inputs may be subjected to derivations inorder to determine rates of change of those inputs. An indication tochange rescuers may be generated when the rate of change in the qualityof performance exceeds a preset amount in a negative direction. Also,models may be generated to represent fatigued users, and actual inputsmay be compared to such models to indicate when fatigue is setting infor a real user and to cause an alert to be generated.

In certain instances, such as when the number of rescuers is known, datamay be stored across multiple cycles of chest compression sessions foreach of the s users. For example, the system may identify in earlycycles of a rescue that one of the rescuers has a sudden drop-off inchest compression performance but then recovers, and may store suchunderstanding and use it in subsequent cycles so as to not trigger anindication to change rescuers simply because the particular rescuer ishaving momentary problems. Another rescuer may be seen to have a slowerdrop in performance but may be more erratic in his provision of chestcompressions, so that a system may permit more variability before ittriggers an indication to switch rescuers, since variability by thatuser may not indicate fatigue, but may simply be normal variability inthe manner in which the user performs chest compressions. Other factorsmay also be taken into account in addition to depth and rate ofproviding chest compressions. For example, a heart rate monitor may beapplied to a rescuer and an increase in heart rate may indicate fatigueby the rescuer, and may be used to generate a signal to switch rescuers.Also, the shape of a compression profile may be used, such that a jerkyor sharp profile may indicate fatigue by a user, and also contribute tothe triggering of a signal to switch rescuers.

FIG. 4 is a flowchart of a process for monitoring CPR performance andproviding feedback for improvement of the performance. Generally, theprocess involves automatic monitoring of the performance of a componentof CPR, such as the provision of chest compressions to a victim, and theindication to a provider of such component when they should stopperforming the component and allow another rescuer to perform thecomponent.

The process begins at box 402, where the process monitors, using anaccelerometer puck, chest compressions that are performed on a victim.The process may have been started after rescuers arrived at the scene ofa victim and deployed electrodes and the puck onto the torso of thevictim. The rescuers may have then turned on a defibrillator connectedto the electrodes and puck, and the defibrillator may have begunperforming relevant functions for the rescue, while the rescuersperformed their manual functions. For example, the defibrillator mayhave initially began taking an ECG reading from the victim anddisplaying it to the rescuers on a graphical display, and may haveanalyzed the victim's heart rhythms to determine whether a shockablerhythm existed so that a defibrillating shock could be applied to thevictim. Other relevant analysis and processing may also have beenperformed, and continue to be performed by the defibrillator.

At the same time, one rescuer may have applied the electrodes and thepuck and have begun performing chest compressions on the victim. Suchcompressions may cause the puck to move and accelerate up and down, sothat an accelerometer in the puck generates signals indicative of suchacceleration. The defibrillator may receive such signals and convertthem into indications of the quality of the chest compression, such asindications of how deep each test compression is, and the pace at whichparticular ones of the chest compressions are occurring. The otherrescuer may separately have applied a ventilation bag to the victim'smouth and began squeezing the bag in coordination with the chestcompressions according to a predetermined protocol.

Before the monitoring begins, the process may have gathered certain datato aid in the monitoring. For example, as a rescuer sets up adefibrillator and hooks it to a victim, the defibrillator may ask therescuer (on a display or via a spoken request) whether the rescuer isalone or is being aided, and might also ask how many additional rescuersare available. If the rescuer indicates that he or she is alone, thenthe system may follow a branch of programming that does not recommendswitching of rescuers, but might more aggressively provide feedback inorder to overcome the extra fatigue a solo rescuer will face. If therescuer is accompanied, then the system may subsequently indicate whenrescuers are to switch roles. The system may also assign a label to eachrescuer, such as “Rescuer 1” and “Rescuer 2” or the actual names of therescuers (which could have been programmed previously, such as for EMTswho use the system frequently, or could be obtained, such as by layrescuers speaking their names into the device in response to promptsfrom the device). If there are three or more rescuers, instructions forrotating may be more complex—i.e., involving more than simply aninstruction to switch positions, but instead telling each rescuer whatcomponent of CPR they should be performing for any particular timeperiod.

A determination about the number of rescuers may also be madeinferentially. For example, a ventilation bag may include electronicsthat report to a defibrillator or other box, and the box may sense thatthe bag is being deployed or used, or is being used simultaneous withchest compressions being performed, in order to infer that there are atleast two rescuers. The defibrillator may adjust its operationaccordingly in the manners discussed above in such a situation (e.g. byenabling prompts for rescuers to switch roles).

At box 404, the process generates a chest compression quality scorebased on the observed prior chest compressions. For example, the qualityscore may be computed as a function of the depth and rate of one or morechest compressions that have been observed from the accelerometer puck.One such mechanism for computing a quality score is shown with respectto FIG. 3 above.

At box 406, external information is incorporated into the quality score,meaning that the information is external to the parameters that areindicating the current quality with which a particular component of CPRis being performed. With respect to chest compressions, the externalcomponents may include a pulse rate or respiration rate of a rescuer,indications about how that rescuer's performance degraded in priorsessions, predetermined time limits for the performance of chestcompressions that may trump even adequate performance by a rescuer, andother such factors. Such an external factors may override the generatedquality score, or may be incorporated into the quality score, such as topush it upward or downward depending on what the external factor is. Forexample, if the rescuer's pulse is abnormally high, the process mayindicate that a new rescuer should take over chest compressions inresponse to an observed decrease in performance, in a manner that ismore speedy than if the rescuer were observed to be calmer.

At box 408, a determination is made with regard to whether the qualityof the performance of the CPR component is adequate or not. With respectto chest compressions, adequate quality may largely be a function of thedepth of chest compression and also a function of the rate ofcompression (though to a lesser degree). Other CPR component may havetheir quality determined using other factors and parameters. The overallquality level may be expressed as a threshold number, a threshold rateof change, or other appropriate threshold, which need not be a constantthreshold, but could instead be a threshold that changes over time also.

If the quality is determined to be adequate, the process returns back tobox 402 and continues monitoring the chest compressions using theaccelerometer puck and determining the quality of such compressions.

If the quality is determined to not be adequate, at box 410, the processprovides an indication to the rescuer, and perhaps to others, than aprovider of care should change. For example, the defibrillator may beepmultiple times to indicate that a change in rescuers should occurbetween the tasks or components of chest compressions and operating theventilation bag. Alternatively or in addition, visual indications may begiven on a display of a defibrillator or may be displayed on a devicemounted closer to the location where the rescuer is performing theparticular zo component of CPR, such as adjacent to the hands of therescuer when the hands are pressing on the sternum of a victim. Inaddition, haptic feedback may be provided to the rescuer, such asswitching from periodic (metronomic) vibration in a unit under therescuer's hands, to continuous vibration under the rescuer's hands, oranother change in haptic feedback that differs from the feedback givenwhen no change is to be made.

Using such a process, then, a system may adjust to the capabilities ofvarious caregivers and maintain caregivers in a position to provide aparticular component of care as long as they are able to provide for it.As a result, the system need not be stuck to preset time limits thatmight not reflect the actual standard of care that can be provided, butcan instead vary based on the actual standard of care that is beinggiven by a particular rescuer team in a particular situation. Theprocess could result in better outcomes for victims tended to by suchrescuers, and in a better experience for the rescuers themselves.

In certain circumstances, prompts for performing CPR may change the wayin which CPR is to be performed in response to indications that therehas been a degradation in performance. In particular, prompting of CPRat a sub-optimal level may be provided, as long as that sub-optimallevel is better than wholly fatiguing a rescuer. For example,hemodynamics data indicates that depth of chest compressions may be moreimportant to, victim well-being than is rate of compressions—i.e., itmay essentially not matter how fast you are performing compressions ifnone of those compressions is truly effective. As a result, the systemmay slow a rate (e.g., a metronome) of prompting compressions and maymonitor how the depth of compressions changes in response to theprompted change in rate. Using stores hemodynamic data correlatingdepths and rates to effectiveness, the system may identify amost-preferred rate that maximizes the hemodynamic effect for aparticular rescuer (using, e.g., the well-known Windkessel model orother approach). While such modifications may be made only after sensingthat a particular rescuer is fatiguing, they can also be initiated atother points and in response to other criteria, including by making suchadjustments throughout a rescue cycle (e.g., the rate of a metronome maybe adjusted slightly and essentially continuously, and the combinationof depth and rate that is measured from the rescuer may be input inreal-time to a formula for computing hemodynamic effect, with subsequentchanges in the rate of the metronome being made in an attempt toincrease the hemodynamic effect within bounds of safety).

FIG. 5A shows a defibrillator showing certain types of information thatcan be displayed to a rescuer. In the figure, a defibrillation device500 with a display portion 502 provides information about patient statusand CPR administration quality during the use of the defibrillatordevice. As shown on display 502, during the administration of chestcompressions, the device 500 displays information about the chestcompressions in box 514 on the same display as is displayed a filteredECG waveform 510 and a CO2 waveform 512 (alternatively, an SpO2 waveformcan be displayed).

During chest compressions, the ECG waveform is generated by gatheringECG data points and accelerometer readings, and filtering themotion-induced (e.g., CPR-induced) noise out of the ECG waveform.Measurement of velocity or acceleration of chest compression duringchest compressions can be performed according to the techniques taughtby U.S. Pat. No. 7,220,335, titled Method and Apparatus for Enhancementof Chest Compressions During Chest Compressions, the contents of whichare hereby incorporated by reference in their entirety. Displaying thefiltered ECG waveform helps a rescuer reduce interruptions in CPRbecause the displayed waveform is easier for the rescuer to decipher. Ifthe ECG waveform is not filtered, artifacts from manual chestcompressions can make it difficult to discern the presence of anorganized heart rhythm unless compressions are halted. Filtering outthese artifact can allow rescuers to view the underlying rhythm withoutstopping chest compressions.

The CPR information in box 514 is automatically displayed whencompressions are detected by a defibrillator. The information about thechest compressions that is displayed in box 514 includes rate 518 (e.g.,number of compressions per minute) and depth 516 (e.g., depth ofcompressions in inches or millimeters). The rate and depth ofcompressions can be determined by analyzing accelerometer readings.Displaying the actual rate and depth data (in addition to, or insteadof, an indication of whether the values are within or outside of anacceptable range) can also provide useful feedback to the rescuer. Forexample, if an acceptable range for chest compression depth is 1.5 to 2inches, providing the rescuer with an indication that his/hercompressions are only 0.5 inches can allow the rescuer to determine howto correctly modify his/her administration of the chest compressions(e.g., he or she can know how much to increase effort, and not merelythat effort should be increased some unknown amount).

The information about the chest compressions that is displayed in box514 also includes a perfusion performance indicator (PPI) 520. The PPI520 is a shape (e.g., a diamond) with the amount of fill that is in theshape differing over time to provide feedback about both the rate anddepth of the compressions. When CPR is being performed adequately, forexample, at a rate of about 100 compressions per minute (CPM) with thedepth of each compression greater than 1.5 inches, the entire indicatorwill be filled. As the rate and/or depth decreases below acceptablelimits, the amount of fill lessens. The PPI 520 provides a visualindication of the quality of the CPR such that the rescuer can aim tokeep the PPI 520 completely filled.

As shown in display 500, the filtered ECG waveform 510 is a full-lengthwaveform that fills the entire span of the display device, while thesecond waveform (e.g., the CO2 waveform 512) is a partial-lengthwaveform and fills only a portion of the display. A portion of thedisplay beside the second waveform provides the CPR information in box514. For example, the display splits the horizontal area for the secondwaveform in half, displaying waveform 512 on left, and CPR informationon the right in box 514.

The data displayed to the rescuer can change based on the actions of therescuer. For example, the data displayed can change based on whether therescuer is currently administering CPR chest compressions to thepatient. Additionally, the ECG data displayed to the user can changebased on the detection of CPR chest compressions. For example, anadaptive filter can automatically turn ON or OFF based on detection ofwhether CPR is currently being performed. When the filter is on (duringchest compressions), the filtered ECG data is displayed and when thefilter is off (during periods when chest compressions are not beingadministered), unfiltered ECG data is displayed. An indication ofwhether the filtered or unfiltered ECG data is displayed can be includedwith the waveform.

Also shown on the display is a reminder 521 regarding “release” inperforming chest compression. Specifically, a fatigued rescuer may beginleaning forward on the chest of a victim and not release pressure on thesternum of the victim at the top of each compression. This can reducethe perfusion and circulation accomplished by the chest compressions.The reminder 521 can be displayed when the system recognizes thatrelease is not being achieved (e.g., signals from an accelerometer showan “end” to the compression cycle that is flat and thus indicates thatthe rescuer is staying on the sternum to an unnecessary degree). Such areminder can be coordinated with other feedback as well, and can bepresented in an appropriate manner to get the rescuer's attention. Thevisual indication may be accompanied by additional visual feedback nearthe rescuer's hands, and by a spoken or tonal audible feedback,including a sound that differs sufficiently from other audible feedbackso that the rescuer will understand that release (or more specifically,lack of release) is the target of the feedback.

FIG. 5B shows the same defibrillator, but when performance of chestcompressions has fallen below a determined quality standard. In thisexample, an alert box 522 is now shown across the bottom half of thedisplay and over the top of information that was previously displayed toprovide feedback to cause the rescuer to improve their administration ofchest compressions. While the user can continue to perform chestcompressions, the blockage of feedback information may further inducethe fatigued user to stop performing chest compressions, and theinformation is more likely to be observed quickly by the rescuer sinceit is placed in an area on the display where the rescuer will already belooking for feedback.

FIGS. 6A-6C show example screens that may be displayed to a rescuer on adefibrillator. Each of the displays may be supplemented with a displaylike box 522 in FIG. 5B when the defibrillator determines that rescuersproviding a certain component of care (e.g., chest compressions) shouldbe changed.

FIG. 6A shows exemplary information displayed during the administrationof CPR chest compressions, while FIGS. 6B and 6C show exemplaryinformation displayed when CPR chest compressions are not being sensedby the defibrillator. The defibrillator automatically switches theinformation presented based on whether chest compressions are detected.An exemplary modification of the information presented on the displaycan include automatically switching one or more waveforms that thedefibrillator displays. In one example, the type of measurementdisplayed can be modified based on the presence or absence of chestcompressions. For example, CO2 or depth of chest compressions may bedisplayed (e.g., a CO2 waveform 620 is displayed in FIG. 6A) during CPRadministration, and upon detection of the cessation of chestcompressions, the waveform can be switched to display an SpO2 or pulsewaveform (e.g., an SpO2 waveform 622 is displayed in FIG. 6B).

Another exemplary modification of the information presented on thedisplay can include automatically adding/removing the CPR informationfrom the display upon detection of the presence or absence of chestcompressions. As shown in FIG. 6A, when chest compressions are detected,a portion 624 of the display includes information about the CPR such asdepth 626, rate 628, and PPI 630. As shown in FIG. 6B, when CPR ishalted and the system detects the absence of CPR chest compressions, thedefibrillator changes the CPR information in the portion 624 of thedisplay, to include an indication 632 that the rescuer should resumeCPR, and an indication 634 of the idle time since chest compressionswere last detected. In a similar manner, when the defibrillatordetermines that rescuers should change, the label 632 can change to amessage such as “Change Who is Administering CPR.” In other examples, asshown in FIG. 6C, when CPR is halted, the defibrillation device canremove the portion of the display 624 previously showing CPR data andcan display a full view of the second waveform. Additionally,information about the idle time 636 can be presented on another portionof the display.

FIGS. 7A and 7B show defibrillator displays that indicate to a rescuerlevels of perfusion being obtained by chest compressions that therescuer is performing. FIG. 7A shows exemplary data displayed during theadministration of CPR chest compressions when the CPR quality is withinacceptable ranges, while FIG. 7B shows modifications to the display whenthe CPR quality is outside of the acceptable range.

In the example shown in FIG. 7B, the rate of chest compressions hasdropped from 154 compressions per minute (FIG. 7A) to 88 compressionsper minute. The defibrillator device determines that the compressionrate of 88 compressions per minute is below the acceptable range ofgreater than 100 compressions per minute. In order to alert the userthat the compression rate has fallen below the acceptable range, thedefibrillator device provides a visual indication 718 to emphasize therate information. In this example, the visual indication 718 is ahighlighting of the rate information. Similar visual indications can beprovided based on depth measurements when the depth of the compressionsis shallower or deeper than an acceptable range of depths. Also, whenthe change in rate or depth indicates that a rescuer is becomingfatigued, the system may display a message to switch who is performingthe chest compressions, and may also emit aural or haptic feedback tothe same effect.

In the examples shown in FIGS. 7A and 7B, a perfusion performanceindicator (PPI) 716 provides additional information about the quality ofchest compressions during CPR. The PPI 716 includes a shape (e.g., adiamond) with the amount of fill in the shape differing based on themeasured rate and depth of the compressions. In FIG. 7A, the depth andrate fall within the acceptable ranges (e.g., at least 100compressions/minute (CPM) and the depth of each compression is greaterthan 1.5 inches) so the PPI indicator 716a shows a fully filled shape.In contrast, in FIG. 7B, when the rate has fallen below the acceptablerange, the amount of fill in the indicator 716b is lessened such thatonly a portion of the indicator is filled. The partially filled PPI 716bprovides a visual indication of the quality of the CPR is below anacceptable range.

As noted above with respect to FIG. 5A, in addition to measuringinformation about the rate and depth of CPR chest compressions, in someexamples the defibrillator provides information about whether therescuer is fully releasing his/her hands at the end of a chestcompression. For example, as a rescuer tires, the rescuer may beginleaning on the victim between chest compressions such that the chestcavity is not able to fully expand at the end of a compression. If therescuer does not fully release between chest compressions the quality ofthe CPR can diminish. As such, providing a visual or audio indication tothe user when the user does not fully release can be beneficial. Inaddition, such factors may be included in a determination of whether therescuer's performance has deteriorated to a level that the rescuershould be instructed to permit someone else perform the chestcompressions, and such information may be conveyed in the variousmanners discussed above.

As shown in FIG. 8A, a visual representation of CPR quality can includean indicator of CPR compression depth such as a CPR depth meter 820. TheCPR depth meter 820 can be automatically displayed upon detection of CPRchest compressions.

On the CPR depth meter 820, depth bars 828 visually indicate the depthof the administered CPR compressions relative to a target depth 824. Assuch, the relative location of the depth bars 828 in relation to thetarget depth 824 can serve as a guide to a rescuer for controlling thedepth of CPR compressions. For example, depth bars 828 located in aregion 822 above the target depth bar 824 indicate that the compressionswere shallower than the target depth, and depth bars 828 located in aregion 826 below the target depth bar 824 indicate that the compressionswere deeper than the target depth. Again, then depth is inadequate(along with perhaps other factors) for a sufficient time to indicatethat the rescuer is fatiguing, an indicator to switch rescuers may beprovided in the manners discussed above.

While the example shown in FIG. 8A displayed the target depth 824 as asingle bar, in some additional examples, the target depth can bedisplayed as a range of preferred depths. For example, two bars 829a and829b can be included on the depth meter 820 providing an acceptablerange of compression depths (e.g., as shown in FIG. 8B). Additionally,in some examples, compressions that have depths outside of an acceptablerange can be highlighted in a different color than compressions thathave depths within the acceptable range of compression depths.

The depth bars 828 displayed on the CPR depth meter 820 can representthe compression depths of the most recent CPR compressions administeredby the rescuer. For example, the CPR depth meter 820 can display depthbars 828 for the most recent 10-20 CPR compressions (e.g., the mostrecent 10 CPR compressions, the most recent 15 compressions, the mostrecent 20 CPR compressions). In another example, CPR depth meter 820 candisplay depth bars 828 for CPR compressions administered during aparticular time interval (e.g., the previous 10 seconds, the previous 20seconds).

In some additional embodiments, physiological information (e.g.,physiological information such as end-tidal CO2 information, arterialpressure information, volumetric CO2, pulse oximetry (presence ofamplitude of waveform possibly), and carotid blood flow (measured byDoppler) can be used to provide feedback on the effectiveness of the CPRdelivered at a particular target depth. Based on the physiologicalinformation, the system can automatically determine a target CPRcompression depth (e.g., calculate or look-up a new CPR compressiontarget depth) and provide feedback to a rescuer to increase or decreasethe depth of the CPR compressions. Thus, the system can provide bothfeedback related to how consistently a rescuer is administering CPRcompressions at a target depth, and feedback related to whether thetarget depth should be adjusted based on measured physiologicalparameters. If the rescuers does not respond to such feedback andcontinues performed sub-optimal CPR, the system may then display anadditional message to switch out the person performing CPR chestcompressions.

In some examples, the system regularly monitors and adjusts the targetCPR compression depth. In order to determine a desirable target depth,the system makes minor adjustments to the target CPR compression depthand observes how the change in compression depth affects the observedphysiological parameters before determining whether to make furtheradjustments to the target compression depth. More particularly, thesystem can determine an adjustment in the target compression depth thatis a fraction of an inch and prompt the rescuer to increase or decreasethe compression depth by the determined amount. For example, the systemcan adjust the target compression depth by 0.1-0.25 inches (e.g., 0.1inches to 0.15 inches, 0.15 to 0.25 inches, about 0.2 inches) andprovide feedback to the rescuer about the observed compression depthbased on the adjusted target compression depth. Then, over a set periodof time, the system can observe the physiological parameters and, basedon trends in the physiological parameters without making furtheradjustments to the target compression depth and at the end of the settime period, may determine whether to make further adjustments to thetarget compression depth.

And again, the actual performance of the rescuer against the revisedtarget may be continually monitored to determine when the rescuer'sperformance has fallen below an acceptable level, so that the rescuerand perhaps others may be notified to change who is performing the chestcompressions. Also, each of the relevant parameters of patient conditiondiscussed above with respect to the various screenshots may be made oneof multiple inputs to a process for determining when rescuers who areperforming one component of a rescue technique should be switched outwith another rescuer, such as for reasons of apparent fatigue on thepart of the first rescuer.

While at least some of the embodiments described above describetechniques and displays used during manual human-delivered chestcompressions, similar techniques and displays can be used with automatedchest compression devices such as the AUTOPULSE device manufactured byZOLL Medical, MA.

The particular techniques described here may be assisted by the use of acomputer-implemented medical device, such as a defibrillator thatincludes computing capability. Such defibrillator or other device isshown in FIG. 9, and may communicate with and/or incorporate a computersystem 800 in performing the operations discussed above, includingoperations for computing the quality of one or more components of CPRprovided to a victim and generating feedback to rescuers, includingfeedback to change rescuers who are performing certain components of theCPR. The system 900 may be implemented in various forms of digitalcomputers, including computerized defibrillators laptops, personaldigital assistants, tablets, and other appropriate computers.Additionally the system can include portable storage media, such as,Universal Serial Bus (USB) flash drives. For example, the USB flashdrives may store operating systems and other applications. The USB flashdrives can include input/output components, such as a wirelesstransmitter or USB connector that may be inserted into a USB port ofanother computing device.

The system 900 includes a processor 910, a memory 920, a storage device930, and an input/output device 940. Each of the components 910, 920,930, and 940 are interconnected using a system bus 950. The processor910 is capable of processing instructions for execution within thesystem 900. The processor may be designed using any of a number ofarchitectures. For example, the processor 910 may be a CISC (ComplexInstruction Set Computers) processor, a RISC (Reduced Instruction SetComputer) processor, or a MISC (Minimal Instruction Set Computer)processor.

In one implementation, the processor 910 is a single-threaded processor.In another implementation, the processor 910 is a multi-threadedprocessor. The processor 910 is capable of processing instructionsstored in the memory 920 or on the storage device 930 to displaygraphical information for a user interface on the input/output device940.

The memory 920 stores information within the system 900. In oneimplementation, the memory 920 is a computer-readable medium. In oneimplementation, the memory 920 is a volatile memory unit. In anotherimplementation, the memory 920 is a non-volatile memory unit.

The storage device 930 is capable of providing mass storage for thesystem 900. In one implementation, the storage device 930 is acomputer-readable medium. In various different implementations, thestorage device 930 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device.

The input/output device 940 provides input/output operations for thesystem 900. In one implementation, the input/output device 940 includesa keyboard and/or pointing device. In another implementation, theinput/output device 940 includes a display unit for displaying graphicaluser interfaces.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform a certain activity orbring about a certain result. A computer program can be written in anyform of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment.

Suitable processors for the execution of a program of instructionsinclude, by way of example, both general and special purposemicroprocessors, and the sole processor or one of multiple processors ofany kind of computer. Generally, a processor will receive instructionsand data from a read-only memory or a random access memory or both. Theessential elements of a computer are a processor for executinginstructions and one or more memories for storing instructions and data.Generally, a computer will also include, or be operatively coupled tocommunicate with, one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of non-volatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,ASICs (application-specific integrated circuits).

To provide for interaction with a user, the features can be implementedon a computer having an LCD (liquid crystal display) or LED display fordisplaying information to the user and a keyboard and a pointing devicesuch as a mouse or a trackball by which the user can provide input tothe computer.

The features can be implemented in a computer system that includes aback-end component, such as a data server, or that includes a middlewarecomponent, such as an application server or an Internet server, or thatincludes a front-end component, such as a client computer having agraphical user interface or an Internet browser, or any combination ofthem. The components of the system can be connected by any form ormedium of digital data communication such as a communication network.Examples of communication networks include a local area network (“LAN”),a wide area network (“WAN”), peer-to-peer networks (having ad-hoc orstatic members), grid computing infrastructures, and the Internet.

The computer system can include clients and servers. A client and serverare generally remote from each other and typically interact through anetwork, such as the described one. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

Many other implementations other than those described may be employed,and may be encompassed by the following claims.

1-24. (canceled)
 25. A system for managing cardiopulmonary resuscitation(CPR) treatment to a person in need of emergency assistance, the systemcomprising: a sensor interface configured to receive input from one ormore sensors adapted to measure information indicative of CPR beingprovided to the person in need of emergency assistance; processingcircuitry operatively coupled with the sensor interface and configuredto receive input from the one or more sensors, and to generate anindication of quality of the CPR being provided to the person in need ofemergency assistance; and an output interface in communication with theprocessing circuitry and configured to generate a pattern of hapticfeedback for a rescuer based on the indication of the quality of theCPR.
 26. The system of claim 25, wherein the output interface isconfigured to generate at least one of audible feedback and visualfeedback based on the indication of the quality of the CPR.
 27. Thesystem of claim 25, wherein the sensor interface is configured toreceive input from an accelerometer.
 28. The system of claim 25, whereinthe indication of quality of the CPR is based on one or more target CPRparameters.
 29. The system of claim 28, wherein the one or more targetCPR parameters include at least one of a chest compression parameter anda ventilation parameter.
 30. The system of claim 29, wherein the chestcompression parameter is based on at least one of chest compressiondepth and chest compression rate.
 31. The system of claim 25, whereinthe indication of quality of the CPR includes a quality score of the CPRadministered to the person in need of emergency assistance.
 32. Thesystem of claim 31, wherein the indication of quality of the CPRincludes a determination of whether the quality score falls within anacceptable range based on one or more target CPR parameters.
 33. Thesystem of claim 31, wherein the quality score is indicative of aninstantaneous quality of CPR administered to the person in need ofemergency assistance.
 34. The system of claim 31, wherein the qualityscore is indicative of an average quality of CPR administered to theperson in need of emergency assistance.
 35. The system of claim 25,further comprising defibrillation electrodes adapted to be operativelyconnected with a defibrillator for providing electrotherapy to theperson in need of emergency assistance.
 36. The system of claim 25,wherein the output interface is arranged so as to rest adjacent arescuer's hands during performance of CPR chest compressions.
 37. Thesystem of claim 25, further comprising a housing that includes the oneor more sensors adapted to measure information indicative of CPR beingprovided to the person in need of emergency assistance.
 38. The systemof claim 37, wherein the one or more sensors include at least oneaccelerometer.
 39. The system of claim 37, wherein the housing includesthe output interface for generating the pattern of haptic feedback basedon the indication of the quality of the CPR.
 40. The system of claim 25,wherein the processing circuitry is configured to generate a signal viathe output interface to switch rescuers performing CPR based on theindication of quality of the CPR being provided to the person in need ofemergency assistance.
 41. The system of claim 40, wherein the pattern ofhaptic feedback includes the signal to switch rescuers performing CPR.42. The system of claim 25, wherein the pattern of haptic feedbackincludes a periodic vibration.
 43. The system of claim 42, wherein theperiodic vibration provides an indication to the rescuer of a targetrate of chest compressions to be administered.
 44. The system of claim25, wherein the pattern of haptic feedback includes a continuousvibration.